CS196268B2 - Lubricant for metals hot shaping - Google Patents

Abstract

1438215 High temperature metal working lubricant LONZA Ltd 15 Oct 1974 [8 May 1974 6 Sept 1974] 44571/74 Heading C5F A high temperature metal working lubricant comprising by wt. (a) 10-90% graphite, (b) 2-60% polymer or copolymer of an ethylenically unsaturated compound, (c) 0À2-8% dispersion or suspension agent, (d) 0-40% film stabilizer. The unsaturated monomers may be vinyl esters, allyl esters, mono- or diolefins, acrylic acid or esters thereof, styrene or unsaturated dicarboxylic acid esters. The dispersion or suspension agent (c) may be a polysaccharide, an alkyl cellulose, or an alginate. The film stabilizer (d) may be a sodium silicate, boron oxide, a phosphate, silicic acid or a mixture thereof. Polymers used in the examples are a vinylacetate-dibutyl maleate copolymer, polyisobutylene, acrylic acid-styrene copolymer, ethylene - vinylacetate copolymer and polyvinylacetate.

Description

LONZA A.G., GAMPEL / WALLIS (BASE), BASEL (Switzerland) (54) Lubricant for thermoforming of metals

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-forming metal lubricant useful at high temperatures. . tách.

It is known to use mixtures of graphite and oil as high temperature lubricants. When using these products, oil degradation occurs, which adversely affects the properties of tools and workpieces and oil degradation products annoys the environment.

For example, it has been proposed to use a precisely defined mixture of alkali metal sulphate, borax, potassium chloride, sodium triacetate and graphite, as well as other additives, in the form of an aqueous dispersion as high temperature lubricants for non-chip metal forming (DAS 2,046,727). This is to ensure that the liquid melt necessary for the thermoforming of metals is available.

It is also known to produce a high temperature lubricant for thermoforming metals from a melt of alkali metal phosphates and borates and optionally zinc and / or aluminum and the addition of other components (DAS No. 2,154,232). .

Finally, a solid lubricant consisting mainly of graphite or tungsten sulfide and sodium fluoride has been proposed. The lubricant is to be used as a paste (DAS 2 028 804).

However, even salt melts cannot always fully satisfy, especially in the production of seamless tubes on the so-called return line or continuous line.

High-temperature forming results in very high temperatures, whereby the viscosity of these melts decreases so that the lubricant film no longer guarantees sufficient lubrication.

The invention is intended to overcome these disadvantages.

According to the invention, this is achieved by a high-temperature lubricant consisting of up to 90% graphite with a grain size of not more than 300 μΐη and a purity of at least 96%, up to 60% of copolymers based on olefins and / or vinyl compounds and / or vinyl compounds of molecular weight

100,000 to 1,000,000

0.2 to 8% of dispersant and optionally up to 40% of sodium silicate, boron oxide, phosphate, silicic acid or a mixture thereof as a film stabilizer.

The lubricant according to the invention is produced, for example, by introducing graphite into an aqueous suspension of an olefin and / or vinyl compound-based polymer or copolymer and a dispersing agent. % of the composition, wherein the solids content is from 32 to 90. % graphite. 2 to 60% by weight of polymer or copolymer; and 0.2 to 6% by weight of dispersant.

The lubricants according to the invention are used in the form of an aqueous suspension having a solids content of 5 to 60%. ·

The lubricants according to the invention can in principle be used for 'metal-free metal forming', for example, in die forging. A preferred form is the lubrication of a mandrel in the production of seamless pipes, for example on a so-called return line, continuous line or MPM line.

According to a preferred embodiment of the invention this is achieved by a lubricant consisting of up to 90% graphite, up to 40% olefin-based polymer or copolymer. and / or vinyl compounds and

0.5 to 6% dispersant.

According to another preferred embodiment of the invention, the lubricant consists of

- - up to 90% - graphite, ........ .......

- - up to 60% - '-' - or - - olefin-based and / or vinyl-based copolymers' (cf) (cf), ...............

0.5 to 6% dispersant, up to 40% film stabilizer.

The lubricant may also be prepared by: - dry mixing of graphite, an olefin and / or vinyl compound-based polymer or copolymer, a dispersant and a film stabilizer, wherein the blend comprises - 32 to 90% graphite, 2 to 60 - % of the polymer or copolymer and 0.2 to 6% of the dispersant and immediately prior to use are suspended in water so as to form an aqueous suspension containing a solid substance of 5 to 60%. ° / o. In addition, from 2 to 40% of the film stabilizer is admixed to the dry mixture. The polymers - or copolymers based on olefins - and / or - vinyl compounds are produced by the emulsion-polymerization process. For example, polymers or copolymers of viresters, such as ethyl acetate, vinyl propionate, vinyl laurate, allyl esters, monoolefins or diolefins can be used. such as ethylene, butadlon, acrylic acid, rhethacrylic acid, styrene, unsaturated dicarboxylic acid esters such as maleic acid esters and the like.

Sodium silicates, boron oxides, phosphates, silicic acid, alone or in admixture with each other, are used as film stabilizers.

The lubricant film must be dry to achieve optimum lubrication performance. Aqueous suspension containing. lubricants - applied in a known manner, such as by spraying or painting, on a hot tool. The water is evaporated and the polymer or copolymer melts to form a viscous film. The film thickness is suitably 0.05 to 1.0 mm, preferably 0.1 to 0.2 mm.

In this film, the graphite particles orient uniformly throughout the surfaces according to their structure in the flakes. At the beginning of the forming process - the workpiece somehow floats on the polymer film. Then the polymer or copolymer burns cleanly, leaving no residue. Opal creates a gas cushion that supports the separation of the friction surfaces. At the same time, the graphite forms a carrier separating and lubricating layer which is effective at local overload and thereby tearing off the hydrodynamically acting melt film and, in particular, at peak temperatures during the process. · ··

The additive opal according to the invention produces a kind of atmosphere between the tool and the workpiece, the effect of which increases the opacity of the graphite at higher temperatures.

The graphite used in the lubricant according to the invention has a grain size of at most 300 µm and a purity of at least 96%, preferably a grain size of up to 100 µτα. and purity 99.5%.

The stabilizer (dispersant) used is a polysaccharide, an alkylcellulose, for example methylcellulose or alginate. Advantageously, a small amount of wetting agent may also be added to the suspension.

Optionally, a small amount of additives such as microbiological adjuvants and corrosion inhibitors can also be admixed with the lubricant according to the invention.

The lubricant according to the invention can in principle be used for metal-free chip-free forming.

Preferred form of use of the lubricant according to the invention is shape rolling. Even at a temperature of 900 ° C and above, the lubricant film is stable and effective.

Example 1

To an aqueous suspension containing 31.1% ethyl acetate. 60 to 20% by weight of lvinylacetate copolymer and an average molecular weight of 1,000,000 and 3,3% of the polysaccharide are mixed with graphite and water to form a slurry containing. ·

-% graphite,

9.5% ethylene vinyl acetate copolymer.

% polysaccharide and

69.5% water.

This mixture according to the invention is sprayed onto the mandrel in the production of seamless tubes by the MPM line.

The composition of the lubricant permits the film _'by: spraying a liquid onto the surface of the mandrel during the return. On the hot surface of the mandrel, the eye is opened. it creates a dry, water-repellent film. Immediately - after applying the film, the mandrel can be cooled in a water bath - or by spraying water without flushing the lubricant film. The lubricant film is not damaged by the intensive cooling of the rollers with water to which the mandrel is exposed at the beginning of the rolling process.

The use of the lubricant according to the invention gives rise to advantages such as that of the prior art lubricants

19626В suspended in water, 'physiologically harmless composition, pure opal (none, unpleasant oil smoke around). The grease leaves the surface of the mandrel shiny, with no residue. The power required to draw the tube through the rolling stand is greatly reduced, the rolling stand operates more evenly, and the mandrel wear is much less. The mandrel tube spans evenly, resulting in better tube quality, and finally, it is also possible to reach the tube with thinner walls.

Example 2 ·

An aqueous dispersion of a mixture of vinyl acetate and dibutyl maleate polymer and polysaccharide can be charged with graphite to give a final concentration of U of graphite, 7-7% of the mixture of vinyl acetate and dibutyl maleate polymer.

0.5% polysaccharide and 1.7% water.

The suspension is applied to the tool or workpiece in a conventional manner by spraying or painting. evaporation of water remains on the surface of the lubricant film.for high temperatures.

Example 3

Lubricants, 69.4% graphite, 29.7% ethylene-vinyl acetate copolymer, and 0.9 percent polysaccharide were dry blended. A suspension is prepared with water just prior to use, the solids being adjusted to 50% of the total weight of the suspension. The lubricant suspension is applied to the tool or workpiece as described.

Example 4

Polysaccharide, colloidal silicic acid, aqueous sodium silicate solution of 38/40 Bé and graphite are mixed into the aqueous polyisobutylene polymer dispersion to give the following concentrations:

• 20% graphite,% polyisobutyl polymer,% colloidal silicic acid,% sodium silicate solution,% polysaccharide and% water.

This suspension may be applied to the workpiece or to the molding tool. The film stabilizer mixture yields a uniform, optimally effective lubricant film even at commonly used forming temperatures, e.g., shape rolling, up to 900 ° C.

Example 1 a d 5

The following powdered components are well mixed or ground dry:

% graphite,% acrylic-styrene copolymer,% colloidal silicic acid,% sodium silicate, and% polysaccharide.

At the point of use, shortly before use, the dry mixture is stirred in an equal amount of water to form a suspension with 50% solids. The suspension is sprayable and sprayed onto the workpiece and / or tool, the water evaporating on the hot surface and the lubricant being effective in forming. By using a film stabilizer, the lubricant film is extremely stable even at high temperatures.

SUBJECT

Claims (5)

CLAIMS 1. A heat treatment lubricant for use in high temperatures, comprising: 32 to 90% of graphite having a grain size of 300 μΐ or less and a purity of 96% or more, 2 to 60% of a polymer or copolymer based on olefins and / or vinyl compounds having a molecular weight of 100,000 to 1,000,000; 0.2 to 8% alginate, alkylcellulose, polysaccharide or a mixture thereof as a dispersant. 2. The lubricant of claim 1 further comprising 2 to 40% silica. BACKGROUND OF THE INVENTION sodium, boron oxide, phosphate, silicic acid or mixtures thereof as a film stabilizer. 3. Lubricant according to claim 1, characterized in that it comprises: 47 to 90 ° / o graphite having a grain size of 300 μΐ or less and a purity of 96 or more; 2 to 45% of an olefin and / or vinyl compound based polymer or copolymer having a molecular weight of 100,000 to 1,000,000; and 0.5 to 8% alginate, alkylcellulose, polysaccharide or a mixture thereof as a dispersant. 4. Lubricant according to claim 1, characterized in that it comprises: 35 to 90% of graphite with a grain size of 300 μΐ or less and a purity of not less. , 96 o / o,. 2 to 60% of a polymer or copolymer based on olefins and / or vinyl compounds having a molecular weight of 100,000 to 1,000,000; and 0.2 to 8 o / o, alginate, alkylcellulose, polysaccharide or a mixture thereof as a dispersant, 5. The lubricant of claim 4 further comprising from about 2% to about 40% sodium silicate, boron oxide, phosphate, silicic acid, or mixtures thereof as a film stabilizer,